1. Technical Field
The present invention generally relates to a developing device and an image forming apparatus, such as, a copier, a printer, a facsimile machine, a plotter, or a multifunction peripheral (MFP) including at least two of coping, printing, facsimile transmission, plotting, and scanning, and, more particular, to an agitation of two-component developer therein.
2. Description of the Background Art
Image forming apparatuses, such as copiers, printers, and facsimile machines, form latent images on a latent image bearer, develop the latent images by a developing device, and then transfer the developed image onto a sheet serving as a recording medium.
Latent images are developed with either one-component developer consisting essentially of magnetic or nonmagnetic toner or two-component developer consisting essentially of toner and carrier.
In the two-component developer, while being agitated, toner particles carried by carrier particles are electrically charged by friction so as to electrostatically adhere to the latent image formed on the latent image bearer such as a photoreceptor.
Development devices typically include a development sleeve and an agitation member. The development sleeve causes developer particles to magnetically stand on end on the circumferential surface thereof and carries the developer particles to the latent image bearer. The agitation member agitates the developer and supplies the agitated developer to the development sleeve. The developer is collected in the development device after the toner therein is consumed to developer the latent image.
To attain reliable toner image quality, the concentration of toner and the amount of charge are kept constant.
Since the image density decreases as the toner in developer is consumed, unused toner (i.e., virgin toner) is supplied to the developing device accordingly.
The supplied toner is agitated, mixed in developer, and thus electrically charged through friction.
To agitate two-component developer in the development device, JP-2012-32488-A proposes a configuration in which a developer chamber includes partitioned conveyance channels (i.e., first and second conveyance paths), and the developer in the conveyance channels are transported in different directions by respective developer conveying members (i.e., screw augers).
In this configuration, developer is circulated between the first conveyance path through which developer is supplied to the developer bearer and the second conveyance path in which the supplied toner is mixed in the developer. Additionally, the developer in the second conveyance path is transported to the first conveyance path.